The present invention relates to liquid hard surface cleaners, and in particular to hard surface cleaners which contain bleach.
Hard surface cleaners containing bleach are well known in the art. Typical compositions comprise one or more surfactants in solution and a bleaching agent such as a it hypochlorite salt. Such hard surface cleaners typically are rather viscous liquids such that when they are applied to a tilted or vertical surface they do not run off immediately, but rather cling to the surface and only gradually drain off thus extending their action on that surface.
Theta may contain other components as well, particularly an abrasive. The abrasive particles should stay suspended in the liquid so that sedimentation of the particles is presented and the product need not be shaken before use.
Often, the required thickening of the liquid cleaner is the result of a proper selection of the surfactant or surfactants, which in combination with other ingredients present in the product or with each other provide for the thickening effect.
Bleach is present in the product because it is very effective in removing oxidizable stains and against microbes and molds. The principal problem normally associated with the presence of bleach is oxidation of other components of the formulation thereby reducing its effectiveness. Excessive decomposition of hypochlorite may also cause the product to foam and pressure to build up in the container of the product.
Thus in EP-A-0 009 942, which describes liquid cleaning compositions containing abrasive and chlorine bleach, it is stressed that that the surfactants should be resistant to oxidation by the bleach. Particularly the ethoxylated nonionic surfactants are mentioned as being unsuitable because of their susceptibility to oxidation. The need to use bleach stable surfactants, particularly bleach stable nonionic surfactants, is also stressed in U.S. Pat. No. 5,279,755, which again describes bleach containing liquid abrasive cleaning compositions. Similar disclosures can be found in EP-A-0 159 923, U.S. Pat. No. 4,438,016 and EP-A-0 649 898. All of these references describe the use of a mixture of anionic and bleach stable nonionic surfactants as being particularly suitable. Tertiary amine oxides are generally recognized as being particularly stable against bleach and very suitable for the above purpose.
U.S. Pat. No. 3,577,347 describes solid cleaning compositions comprising a surfactant, a chlorine bleach and a water soluble salt as abrasive. Large groups of anionic and nonionic surfactants are listed as suitable, among which ethoxylated alkylphenols and ethoxylated fatty alcohols. However, it is stressed that in order to remain stable the composition should not contain an appreciable amount of water and the water soluble salt should therefor have less than 6 molecules of water of hydration.
EP-A-0 346 112 discloses machine diswashing compositions containing hypochlorite bleach. The compositions also contain detergent surfactants of which it is stressed that they should be bleach stable. A general description of a wide variety of possible nonionic surfactants, including fatty alcohol ethoxylates, ends with the remark that some of them are bleach stable and some are not. It is then said that in order to be bleach stable the nonionic detergent compound should not contain free OH groups, i.e. it should be xe2x80x9ccappedxe2x80x9d with a low alcohol moiety. Also the compositions should preferably have pH between 10.5 and 12.5 to minimize chemical interaction between the detergent and the bleach.
Similar compositions are described in U.S. Pat. No. 5,130,043 which also contain alkoxylated nonionics which are capped, i.e. do not contain a free terminal OH group.
Further examples of the use of capped alkoxylated nonionic surfactants in combination with hypochlorite bleach may be found in EP-A-0 812 908.
EP-A-0 520 226 describes acidic halogen bleach compositions which contain limited amounts of ethoxylated alkylphenols as chlorine scavenger. This shows the ease with which these compounds react with halogen.
Nonionic surfactants which are generally considered to be bleach stable are not always the most desirable ones to be used in cleaning compositions. Thus, amine oxides are generally more expensive than e.g. ethoxylated aliphatic alcohols. Also, the latter are generally considered to be excellent detergents especially for removing fatty soils.